Resistor for spark plug

ABSTRACT

There is provided a resistor for spark plugs used in an internal combustion engine. The resistor comprises a resistance material consisting of tantalum oxide, tin oxide and antimony oxide in proper proportion by weight.

' United States Patent [191 Kamigaito et al.

[ RESISTOR FOR SPARK PLUG [75] Inventors: Osami Kamigaito; HideyukiMasaki;

Masami Oki, all of Nagoya; Masatosi Suzuki, Kariya; Yasuo Nakamura,Nagoya, all of Japan 21 Appl. No.: 399,275

[30] Foreign Application Priority Data Sept. 22, 1972 Japan 47-95439[52] US. Cl. 106/46; 117/124 A; 252/518 [51] Int. CL C04B 33/26 [58]Field of Search 106/46, 45, 39.5; 117/124 A; 252/518 [5 6] ReferencesCited UNITED STATES PATENTS 2,152,655 4/1939 McDougal et al. 106/46 XOct. 28, 1975 2,853,392 9/1958 Bousky 106/46 2,864,773 12/1958 Counts etal. 252/503 2,885,521 5/1959 Fotland 106/46 X 3,062,668 11/1962 Pierrotet al l06/39.5 3,235,655 2/1966 Counts et a1 252/520 X 3,658,583 4/1972Ogawa et a]. 106/46 X 3,660,124 5/1972 Yoshioka et a1 106/46 X FOREIGNPATENTS OR APPLICATIONS 1,213,621 11/1970 United Kingdom 106/46 PrimaryExaminer-Allen B. Curtis Assistant Examiner-Thomas A. Waltz Attorney,Agent, or Firm-Cushman, Darby & Cushman [5 7] ABSTRACT There is provideda resistor for spark plugs used in an internal combustion engine. Theresistor comprises a resistance material consisting of tantalum oxide,tin oxide and antimony oxide in proper proportion by weight.

5 Claims, 8 Drawing Figures US. Patent Oct. 28; v1975 CHANGE OFRESISTANCE BEFORE AND AFTER TEST 8 5 sheet 1 of? 3,915,721

FIG.|

ANTIMONY OXIDE ADDED (%BY WEIGHT) RESISTANCE (KQ- cm OUJOI" QCDOO?SPECIFIC QQDOOI ANTIMONY OXIDE ADDED BY WEIGHT) m v E0 av:

TEMPERATURE (C U.S. Patent Oct. 28, 1975 Sheet 6 of? 3,915,721

GLASS BY WEIGHT) U.S. Patent Oct. 28, 1975 Sheet 7 of7 RESISTOR FORSPARK PLUG The present invention relates to spark plugs which do notcause communication radio wave interference, and more particularly thepresent invention relates to a resistor of 3 to kiloohms used withinternal combustion engine spark plugs of the type which are providedwith a center electrode.

In the past, spark plugs heretofore used in internal combustion engineshave been of the type which employ a low resistance center electrode. Adisadvantage of this type of spark plugs is that the radio wavesgenerated upon the production of a spark at the spark plug in servicegives rise to communication radio wave interference. With the recentdevelopment of communications, the consideration of remedial measuresagainst radio wave interference has become increasingly important. Inthe case of the spark plugs for internal combustion engines, theinsertion of a resistor in the electric circuit for the spark plug hasbeen proposed as a means of suppressing the interference and variousmethods have been used for this purpose. These methods may be dividedinto two classes: one in which the resistor is inserted in the sparkplug itself and the other in which the resistor is inserted in the hightension cable for the ignition circuit.

In these remedial measures against radio wave interference, it isrequired that a resistor be used whose resistance values is in the rangebetween 3 to 20 kiloohms at temperatures ranging from the normaltemperature up to 400C.

In the past, spark plugs of the type having a conducting seal composedof a conductive material bonded with a highly heat resisting glassmaterial of low melting point have been extensively used.

Such a conducting glass seal is prepared by mixing a resistance materialsuch as a powdered metal (e.g., copper, iron nickel or nickel-chromiumtype metal) or carbon or a powdered low resistance metal oxide (zincoxide, barium borate, chrome dioxide, chrom trioxide, nickel oxide orthe like) with a powdered low melting glass such as borosilicate typeglass, heating the mixture up to a temperature higher than the softeningtemperature of the glass, and compressing and sealing it in place withthe electrode, thus producing a resistor with this sealed glass member.

However, the specific resistances of spark plug resistors produced inthis manner are all lower than 0.01 kfl-cm and'the insertion of such alow resistance resistor in the spark plug can provide only a resistanceof lower than 0.1 kQ which practically has no noise suppressing effect.While the amount of glass in this resistor may be increased to produce ahigh resistance resistor for spark plugs, the specific resistances ofresistors that may be produced by slightly changing the amount of glassare subject to extremely wide variations ranging from 0.01 to 1000 kQ-cmand thus their manufacture is impractical. Further, in the highresistance spark plug resistor produced by increasing the amount ofglass, the resistance material disperses in the glass material and thusthe resistor is structurally unstable and not well suited for practicaluse.

With a view to overcoming the foregoing difficulty, it is the object ofthe present invention to provide a resistor for spark plugs which iscomposed of a high resistance material having a novel composition andwhich has a high resistance of 3 to 20 kiloohms that is effective insuppressing noise.

The resistor for spark plugs according to the present invention hasamong its great advantages the fact that the specific resistance of theresistor is readily controlled by adjusting the amount of added tantalumoxide and thereforethe resistance value can be easily increased withoutresorting to any complicated procedure of increasing the amount of glassto obtain an increased resistance value. The range of variations of theresistance value of the resistor is narrow and it has a structuralstability with the required resistance value of 3 to 20 kiloohms.Further, a wider range of sintering temperatures usable in themanufacture of this resistor is a great convenience to the manufacturethereof.

Other objects, advantages and features of this invention will becomereadily apparent from considering the following detailed descriptiontaken in conjunction with the accompanying drawings, in which:

FIGS. 1 to 6 are graphs for the experimental examples of this invention,in which:

FIG. 1 shows the relationship between the amount of antimony oxide in aresistor produced by combining tin oxide and antimony oxide togetherwith a glass and the change in resistance before and after sparkdischarge;

FIG. 2 shows the relationship between the amount of antimony oxide in aresistance material consisting of tin oxide and antimony oxide and thespecific resistance thereof;

FIG. 3 shows the relationship between the spark discharge period and thespecific resistance of a resistor according to the present invention;

FIG. 4 shows the relationship between the temperature and the specificresistance of the resistor of FIG. 3;

FIG. 5 shows the relationship between the amount of tantalum oxide inresistance materials and the specific resistance and the resistancevalue of resistors;

FIG. 6 shows the relationship between the amount of glass in theresistor and the specific resistance thereof;

FIG. 7 is a sectional front view of a spark plug having sealed thereinthe resistor according to the present invention; and

FIG. 8 is a sectional front view of another spark plug in which theresistor of this invention is provided in place in the form of arod-shaped resistor.

A novel spark plug resistor provided in accordance with the presentinvention is produced by sintering (bonding), with a low melting glass,a resistance material having the composition: tantalum oxide 1-30 byweight, tin oxide 63-98 by weight and antimony oxide 0.7-9.9 by weight.

In accordance with the present invention, the tantalum oxide consists oftantalum pentoxide (Ta O tin oxide consists of tin monoxide (SnO) or tindioxide (Sno antimony oxide consists of antimony trioxide (Sb O orantimony tetroxide (Sb O and the low melting glass consists ofborosilicate type glass. While the resistance material is composed ofthese oxide of tantalum, tin and antimony in the previously mentionedcomposition ranges, this composition is determined on the followingreasons.

In other words, in order that this resistance material may ensure astable performance of the spark plug, that is, the change of thersistance value of the resistor due to the repeated ignition may bereduced, it is essential that the resistance material contains tin oxideand antimony oxide in proper proportions. Namely, the resistancematerial should comprise between 90-99 (by weight and this is the samewith all other percentages) of tin oxide and between ll% of the antimonyoxide. If the antimony oxide content is less than 1%, the aforesaidstable performance of the spark plug is deteriorated. While the stableperformance is ensured with the antimony oxide content higher than 1 ifthis content is higher than 10 there is an inconvenience in that whenthe resistance material is sintered and bonded using the glass, bubblesproduced enter into the glass phase. However, there is a problem thatmere bonding of the two constituents with the glass results in aresistor whose specific resistance is as low as about 10' l0 kQ-cm andit is difficult to produce the desired resistor. The addition oftantalum oxide is therefore necessary to produce the desired resistancematerial. The proportion of tantalum oxide to be mixed is such that atotal amount of tin oxide and antimony oxide is between 70-90 and theremaining tantalum oxide content is between 30-1 If the tantalum oxidecontent is less than 1 in the case of an ordinarily employed spark plugof practical size, it is difficult to obtain a resistor of over 3kiloohms. On the other hand, if this content is higher than 30 it isdifficult to obtain a resistor of less than 20 kiloohms. As will be seenfrom this fact, the preferred proportions of the constituents in thecomposition of the resistance material as a whole are ultimatelydetermined, as mentioned previously, as follows: tantalum oxide 1-30 tinoxide 63-98 antimony oxide 0.7-9.9

Further, in the resistor according to the present invention, theproportions of the resistance material and the low melting glass shouldpreferably be such that the resistance material is in the range 40-90and the glass is in the range 60-10 When the amount of glass exceeds 60the glass enters between the particles of the resistance material thusincreasing the resistance value considerably, while even a slight changein the amount of glass results in a large variation of the resistancevalue and it is difficult to obtain a resistor with the desiredresistance (FIG. 6). The glass content should preferably be greater thanin order to ensure the bonding of the resistance material. Further, ifthe resistor is sealed in the spark plug, the amount of the glass shouldpreferably be in the range or above from the gastight point of view.

The resistor according to the present invention may be utilized bysealing it in the spark plug between its center electrode and centralconductor as mentioned above, or alternately the resistor may beinserted in the spark plug in the form of a solid resistor or it may beplaced in the high tension conductor cable for the ignition circuitoutside of the spark plug.

When the resistor is to be sealed in the spark plug, as shown in FIG. 7,a resistor 2 is compressed and sealed between a center electrode 3inserted in the lower end of the bore formed in an insulator 4 and acentral conductor I inserted above the center electrode 3, therebyjoining them together. In this case, therefore, the resistor serves notonly to suppress communication radio wave interference, but also toprovide the required electric conduction between the center electrode 3and the central conductor 1 and hermetically seal them to the insulator.In FIG. 7, numeral 5 designates a housing, numeral 6 a ground electrode.

In the spark plug shown in FIG. 8, the resistor according to thisinvention is inserted in the form of a rod-shaped solid resistor. Acenter electrode 3 inserted in the lower end of the bore formed in aninsulator 4' is enclosed by a conventional high-conductive substance 7and a metal conductor 9 is fixedly placed above the substance 7;Disposed above the metal conductor 9 is a spring 8 and a resistor 2according to this invention is placed between this spring 8 and acentral conductor 1'. The central conductor 1 is screwed into the boreof the insulator 4' to securely hold the resistor 2' in place. As aresult, the resistor 2 is not required to serve as a seal as in thespark plug shown in FIG. 7.

As described hereinbefore, the resistor according to the presentinvention comprises a resistance material composed of theabove-mentioned three constituents, i.e., tantalum oxide, tin oxide andantimony oxide and bonded with a low melting glass. This resistor isproduced according to the following procedure: tin oxide and antimonyoxide are mixed and then heated to a high temperature to cause reactionbetween the two elements. The resultant reaction substance is added withtantalum oxide and reheated to an elevated temperature to cause reactiontherebetween. A low melting point glass such as borosilicate glass isadded to the ternary resistance material in fine powder form and a smallquantity of an adhesive substance such as polyvinyl alcohol is alsoadded. These elements are thoroughly mixed together to obtain asubstantially uniform mixture. This mixture is then placed in the sparkplug or alternately it is placed in a molding form, heated to anelevated temperature to soften the glass and then cooled to produce aresistor. When this resistor is to be placed in the spark plug, as inthe case of a conventional sealed-resistor type spark plug, theabovementioned mixture is placed, as shown in FIG. 7, between the centerelectrode 3 and the central conductor 1 and a pressure is applied to thecentral conductor 1 to compress and seal the resistor in place at anelevated temperature, thereby producing the spark plug having theresistor 2 sealed between the central conductor 1 and the electrode 3.On the other hand, when the abovementioned mixture is to be placed inthe molding form, the mixture is inserted for example in a cylindricalmolding form, heated and then cooled to produce a cylindrical resistor.This resistor is inserted, as the resistor 2', between the conductor 9electrically connected to the center electrode 3' and the centralconductor l as shown in FIG. 8.

The effects of the various mixing proportions of the above-describedresistance material and the glass will be described with reference tothe following experimental examples. In the following experimentalexamples, the tin oxide, antimony oxide and tantalum oxide usedconsisted of SnO Sb O and Ta O respectively, and the glass consisted ofborosilicate glass. As will be described in greater detail in connectionwith the description of the experimental examples, each of the resistorsin the experimental examples was produced by mixing given amounts of theresistance material and the glass together, heating the mixture tosoften the glass and then bonding the resistance material with theglass.

Experimental EXAMPLE 1 The test results on the stability of the binarysystem resistance materials consisting of tin oxide and antimony oxidewill be explained with reference to FIG. 1.

In other words, each of the resistance materials produced by mixing tinoxide and antimony oxide in various proportions was sintered using thelow melting glass and the resultant rod-shaped resistor placed in thespark plug in the form of a solid resistor as shown in FIG. 8 was testedby the resistor load life testing method according to .118 5102. FIG. 1shows the results of the tests on the changes in the resistance valuesof the resistors before and after the discharging of spark for a periodof 250 hours. In FIG. 1, the ordinate represents the rate of change ofthe resistance value and the abscissa represents the amount of the addedantimony oxide in the binary resistance materials consisting of tinoxide and antimony oxide.

As will be seen from FIG. 1, if the antimony oxide content is less than1 the change of the resistance value before and after the test isextremely great and the resultant resistor cannot be put in anypractical use. On the other hand, if the antimony oxide content is over1 the change of the resistance value is small and particularly theantimony oxide content of over 2 reduces the change of the resistancevalue to almost naught with resultant superior stability. However, ifthe antimony oxide content exceeds the resistance material will beincreasingly melted into the glass and thus bubbles tend to remain inthe glass, making it foarmy and thus unsuitable to any practical use.

FIG. 2 shows the specific resistance of the binary resistance materialin which tin oxide was caused to react with antimony oxide. In FIG. 2,the ordinate represents the specific resistance (kQ-cm) and the abscissarepresents the amount of the added antimony oxide The ordinate is in thelogarithmic scale and the abscissa is in the uniform scale.

As will be seen from FIG. 2, the specific resistance of the resistorcomprising the bindary system resistance material consisting of tinoxide and antimony oxide is in the very low range of less than 0.00007kQ-cm when the amount of the added antimony oxide is less than 10However, if tantalum oxide is added as a third constituent to theabove-described binary system resistance material, the specificresistance of the resultant material may be increased by about 10 10times. The stability of the ternary system resistance materialcomprising such tin oxide, antimony oxide and tantalum oxide will bedescribed with reference to FIGS. 3 and 4.

FIG. 3 shows the results of the tests conducted according to the loadlife testing method for automobile spark plugs with resistor defined in.IISD 5102 on the resistor composed of the ternary resistance materialcontaining 90 tin oxide, 5 antimony oxide and 5 tantalum oxide and aborosilicate glass mixed with each other in equal proportions. Thespecific resistance (kQ-cm) of the spark plug resistor was checked afterthe spark discharging over a predetermined period of time. In FIG. 3,the ordinate represents the specific resistance and the abscissarepresents the period of spark discharging. In this case, the ordinateand abscissa are both in the logarithmic scales. As will be seen fromFIG. 3, the specific resistance of the resistor shows almost no changewith increase in the spark discharging period and proves that this sparkplug resistor lends itself to be an excellent resistor.

FIG. 4 shows the results of the heat tests conducted on the resistorscomprising the above-described ternary system resistance materialaccording to the method of test for automobile spark plugs with resistordefined in JIS 5102. In FIG. 4, the ordinate represents the specificresistance (kQ-cm) and the abscissa represents the temperature (C) ofthe resistor and the symbol R indicates the fact that the resistor is atthe normal temperature and the specific resistance value indicates theone obtained when the resistor heated to 300C was cooled to the normaltemperature. In FIG. 4, the ordinate is in the logarithmic scale and theabscissa is in the uniform scale.

As will be seen from FIG. 4, the range of variations of the specificresistance is narrow and it is evident that the above-described ternarysystem resistor for spark plugs according to the present invention meetsthe specification of JIS 5102 requiring that the tolerance be in therange i 30 of the rated resistance value. The spark plug resistors usedin the tests of FIGS. 3 and 4 were cylindrical resistors of the samedimensions.

Experimental EXAMPLE 2 The resistance value and specific resistancevalue of a spark plug resistor comprising a resistance materialcontaining tantalum oxide as its third constituent will be describedwith reference to FIG. 5.

In FIG. 5, the ordinate represents the resistance value (kQ) of theresistor and the corresponding specific resistance (kQ-cm) and theabscissa represents the amount of tantalum oxide in the resistancematerial.

In FIG. 5, the lines a, b and c are for the compositions where theproportions of tin oxide and antimony oxide differ from one another.Each of the lines represents the specific resistance and resistancevalue of a resistor in which the above two constituents in predeterminedproportions and tantalum oxide are mixed with each other in varyingproportions and then bonded with the low melting glass. The line a showsthe resistance value (and the specific resistance) of, the spark plugresistors obtained by using resistance materials comprising a binarysystem resistance material containing 99 tin oxide and l antimony oxideand tantalum oxide as a third constitution which are mixed in varyingproportions, and mixing each of these resistance materials and the lowmelting points glass half and half. The line b shows the resistancevalue (and the specific resistance) of the spark plug resistors obtainedby using resistance materials comprising a binary system resistancematerial containing 95 tin oxide and 5 antimony oxide and tantalum oxidewhich are mixed with each other in varying proportions, and mixing eachof these resistance materials and the low, melting glass half and half.The line c shows the resistance value (and the specific resistance) ofthe spark plug resistors obtained by using resistance materialscomprising a binary system resistance material containing 90 tin oxideand IO antimony oxide and tantalum oxide which are mixed with each otherin varying proportions, and mixing each of these resistance materialsand the low melting glass half and half. The resistors used are of therod-shaped type having the dimensions of 2.2 mm length and 3 mmdiameter.

As will be seen from FIG. 5, the resistance value of the resistorincreases in proportion to an increase in the amount of tantalum oxidecontained in the resistance material and this tendency remains the sameindependent of the proportions of tin oxide and antimony oxide in theresistance material. Further, the higher the tin oxide content is, thehigher the resistance value will be. While the line a in FIG. representsthe cases where the binary systems containing 99 tin oxide and lantimony oxide are mixed with tantalum oxide, they show the maximumvalue of tin oxide in the binary systems as mentioned earlier. In eachof these cases, the tantalum oxide content in the resistance materialshould be in the range 1 or above in order that the resistance value ofthe resistor may become higher than 3 kiloohms. In the cases of thelines b and c where the tin oxide content is low, the tantalum oxidecontent of about 2.5 and above 4 respectively, produce the resistors ofover 3 kiloohms. On the other hand, the line c represents the caseswhere the amount of tin oxide in the binary systems is at the minimumvalue of 9 In each of these cases, the amount of tantalum oxide in theresistance material should be less than 30 in order that the resistancevalue of the resistor becomes lower than 20 kiloohms. Further, in thecases of the lines a and b where the tin oxide content is high, it isnecessary that the tantalum oxide content be about 30 and less than 28respectively. It will be seen that by adjusting the amount of tantalumoxide in the resistance material in the range between l-30 the resistorhaving a resistance value of 3 to 20 kiloohms may be obtained. Further,as will be seen from FIG. 6 that will be explained later, thisresistance value may also be varied somewhat by varying the amount ofthe low melting glass mixed with the resistance material.

Experimental EXAMPLE 3 The change of the specific resistance of theresistor with the variations in the proportions of the low melting glassand the resistance material in the mixtures will be described withreference to FIG. 6. In FIG. 6, the ordinate represents the specificresistance (kQ-cm) and the abscissa represents the weight percent of theglass in the resistor comprising the resistance material and the glass.The resistance material used contained 90.25 tin oxide, 4.75 antimonyoxide and 5 tantalum oxide, and this resistance material was mixed withthe borosilicate type glass in varying proportions and the mixtures wereheated up to about 850C to produce the rod-shaped resistors whosespecific resistances were measured.

As will be seen from FIG. 6, when the amount of the added low meltingglass becomes higher than 60 the specific resistance increasesconsiderably, whereas the specific resistance does not show any markedchange with the glass content of less than 60 The present invention willbe described further with reference to the following example.

EXAMPLE 1 In this example, 95 of tin dioxide and 5 of antimony trioxidewere mixed and heated with each other in an alumina crucible at atemperature of 1 100C for 5 hours after which the mixture was cooled tothe normal temperature. 85 of this product and 15 of tantalum pentoxidewere intimately mixed and then reacted with each other at 1 100C for 5hours. The resultant ternary resistance material in granular form wasmixed with 50 of a powdered low melting glass containing borosilicate asits principal element and the mixture added with about 1 of an organicpaste was milled. A given amount of this product was put, as

shown in FIG. 7, in the space above the center electrode 3 in the boreof the insulator 4 and the central conductor 1 was inserted. Afterheating at 850C for 30 minutes, a pressure was applied to the centralconduc- 5 tor l to hot press and seal the product in place where it wasfirmly held and cooled to provide the resistor 2.

The resistance value of the resistor 2 produced in this way and locatedbetween the central conductor 1 and the center electrode 3 was 10kiloohms at the normal temperature while it was 9 kiloohms when heatedto 400C. The gastight tests conducted on this spark plug resistor 2revealed that it was superior showing no leakage even under the appliedpressure of 30 kg/cm Tests conducted by installing this spark plug in anactual automobile engine showed that the amount of the noise producedwas considerably low as compared with that produced by conventionalspark plugs equipped with no resistor.

The above-described resistor comprised 50 of the resistance materialcontaining 80.8 tin dioxide, 4.2 antimony trioxide and tantalumpentoxide and 50 of the glass.

It will thus be seen from the foregoing description that a spark plugresistor according to the present invention is produced by sintering aresistance material containing 1-30 tantalum oxide, 63-98 tin deoxideand 0.7-9.9 antimony trioxide with a low melting glass, and thus it ispossible to provide a spark plug resistor having a resistance value of 3to kiloohms that is essential for the suppression of noises.Particularly, it will be seen that in the resistance material accordingto the present invention, the specific resistance of the binaryresistance material composed of tin dioxide and antimony oxide isincreased from below 10 Q-cm up to l00l0,000 (ll-cm by a small additionof tantalum oxide as the third constituent and in this way theresistance value of the spark plug resistor can be increased withoutresorting to any complicated methods by which the amount of glass isincreased to obtain an increased resistance value. There is thus a greatadvantage of providing a resistor which has a narrow range of variationsof its resistance value and which is also stable structurally. There isa further advantage that the specific resistance can be easilycontrolled by adjusting the amount of the added tantalum oxide.

Further, by virtue of the fact that a resistance material is produced byadding tantalum oxide as the third constituent to tin oxide and antimonyoxide, there is a still further advantage in that when resistancematerial is mixed with a glass and heated to produce a sintered mass,the added tantalum oxides ensure a wider range of the sinteringtemperatures and hence a great convenience in the manufacture of theresistor.

What we claim is:

l. A resistor having a resistance of 3-20 kiloohms for a spark plugcomprising:

40 to 90% by weight of a resistance material, said resistance materialbeing composed of tantalum oxide between lweight percent, tin oxidebetween 63-98 weight percent and antimony oxide between 07-99 weightpercent, and a glass in an amount of 60 to 10% by weight for fixing saidresistance material.

2. A resistor according to claim 1 wherein the glass is a borosilicateglass.

9 10 3. A resistor according to claim 1, wherein the glass oxide andantimony oxide. is between 20 and 60% by weight of the total of glass 5.A resistor according to claim 1 wherein the resisand resistancematerial. tance material is 90% by weight tin oxide, 5% by weight 4. Aresistor according to claim 1 wherein the antiantimony oxide and 5% byweight tantalum oxide.

mony oxide is l to by weight of the total of tin 5

1. A RESITOR HAVING A RESISTANCE OF 3-20 KILOOHMS FOR A SPARK PLUGCOMPRISING: 40 TO 90% BY WEIGHT OF A RESISTANCE MATERIAL, SAIDRESISTANCE MATERIAL BEING CMPOSED OF TATALUM OXIDE BETWEEN 1-30 WEIGHTPERCENT, TIN OXIDE BETWEEN 63-98 WEIGHT PERCENT AND ANTIMONY OXIDEBETWEEN 0.M-9.9 WEIGHT PERCENT, AND A GLASS IN AN AMOUNT OF 60 TO 10% BYWEIGHT FOR FIXING SAID RESISTANCE MATERIAL.
 2. A resistor according toclaim 1 wherein the glass is a borosilicate glass.
 3. A resistoraccording to claim 1, wherein the glass is between 20 and 60% by weightof the total of glass and resistance material.
 4. A resistor accordingto claim 1 wherein the antimony oxide is 1 to 10% by weight of the totalof tin oxide and antimony oxide.
 5. A resistor according to claim 1wherein the resistance material is 90% by weight tin oxide, 5% by weightantimony oxide and 5% by weight tantalum oxide.